Credit

Caption

Lung cancer. Coloured scanning electron micrograph (SEM) of tissue from a lung bronchus affected by adenocarcinoma, cancer arising from the epithelial (lining) tissue. The lining of the lung is brown, cancerous cells are purple, and mucus is grey. Lung cancers are usually caused by tobacco smoking, and are fatal unless caught early. Magnification: x330 when printed at 10 centimetres wide.